Steam Reforming of Ethanol over Ni/Al2O3-La2O3 Catalysts Synthesized by Sol-Gel

The activity of Ni/Al2O3-La2O3 catalysts prepared by sol gel process for hydrogen production using ethanol steam reforming was studied. The effect of Ni and La loading in the reaction activity and hydrogen selectivity was analyzed. The catalytic measurements were performed on a fixed-bed microreactor for a 6 h period; within this time, the catalysts showed partial deactivation. The catalyst containing 12 wt % La showed the highest yield to H-2, but it also presented the highest deactivation. The other catalysts with the same Ni loading showed a decrease in H-2 yield over time. The increase of Ni loading from 5 to 10 wt % caused an increase in H-2 and CO yields in all La containing catalysts. The catalyst supported on sol-gel synthesized alumina showed the highest activity after 6 h on stream. This catalyst showed the lowest deactivation from all the systems that were studied. Polymeric and graphitic carbon were identified by DTA analysis of the spent catalysts. TGA analysis showed that the total coke deposited after reaction followed the trend: Ni/Al > Ni/12La approximate to Ni/8La > Ni/5La. However, less graphitic coke was identified on the catalysts as the lantana loading increased in the supports. Additionally, TEM results indicate that the radius of the graphite tubes decreased as the concentration of Ea in the support increased. A slight increase of H-2 and CO2 yields was obtained when the water to ethanol mole ratio increased from 3 to 6. Higher deactivation was observed when more steam was fed to the reaction, even when lower carbon contents were determined by DTA-TGA analysis.